# include<stdio.h> # include<vector> # include<iostream> # include<algorithm> # include<set> # include<map> # include<string> using namespace std; int main(){ int n,a[1100],b[10000]; cin>>n; for(int i=0;i<n;i++){ cin>>a[i]>>b[i]; int sum1=0,sum2=0; sum2+=b[i]; if(a[i]>a[i+1]) sum1=a[i+1]; for(int j=0;i<n;i++){ if(a[j]==sum1){ sum2+=a[1]*(j-1); sum2+=a[j]*(n-j); } } }cout<<sum2; }